Coagulation diseases, such as von Willebrand Disease (VWD) generally result from a deficiency in the coagulation cascade. von Willebrand Disease (VWD) refers to the group of diseases caused by a deficiency of von Willebrand factor. Von Willebrand factor helps blood platelets clump together and stick to the blood vessel wall, which is necessary for normal blood clotting.
von Willebrand disease (VWD) is the most common inherited bleeding disorder, with an estimated prevalence rate of 1% (Veyradier A, et al., Medicine (Baltimore). 2016, 95(11):e3038). However, excluding milder forms of the disease, only about 1/10,000 patients actually require treatment. Current treatment for these coagulopathies includes a replacement therapy using pharmaceutical preparations comprising the normal coagulation factor.
VWF is a glycoprotein circulating in plasma as a series of multimers ranging in size from about 500 to 20,000 kD. The full length of cDNA of VWF has been cloned; the propolypeptide corresponds to amino acid residues 23 to 764 of the full length prepro-VWF (Eikenboom et al (1995) Haemophilia 1, 77 90). Multimeric forms of VWF are composed of 250 kD polypeptide subunits linked together by disulfide bonds. VWF mediates the initial platelet adhesion to the sub-endothelium of the damaged vessel wall, with the larger multimers exhibiting enhanced hemostatic activity. Multimerized VWF binds to the platelet surface glycoprotein Gp1bα, through an interaction in the A1 domain of VWF, facilitating platelet adhesion. Other sites on VWF mediate binding to the blood vessel wall. Thus, VWF forms a bridge between the platelet and the vessel wall that is essential to platelet adhesion and primary hemostasis under conditions of high shear stress. Normally, endothelial cells secrete large polymeric forms of VWF and those forms of VWF that have a lower molecular weight arise from proteolytic cleavage. The multimers of exceptionally large molecular masses are stored in the Weibel-Pallade bodies of the endothelial cells and liberated upon stimulation by agonists such as thrombin and histamine.
For patients with VWD, it is recommended that they be treated with von Willebrand factor (VWF) replacement given the need for prolonged hemostasis, particularly in major surgery (Mannucci P M and Franchini M., Haemophilia, 2017, 23(2):182-187; National Institutes of Health. National Heart, Lung, and Blood Institute. The Diagnosis, Evaluation, and Management of von Willebrand Disease NIH Publication No. 08-5832; December, 2007). Plasma-derived VWF therapies contain factor VIII (FVIII) and have the potential for FVIII accumulation with repeated dosing. VONVENDI® (von Willebrand factor [recombinant], Shire, Westlake Village, Calif.) is the first and only recombinant VWF (rVWF) concentrate (Turecek P L, et al. Hamostaseologie. 2009; 29(suppl 1):532-38; Mannucci P M, et al. Blood, 2013; 122(5):648-657; Gill J C, et al. Blood, 2015; 126(17):2038-2046).
Gastrointestinal (GI) bleeding events occur in up to 20% of patients with von Willebrand disease (VWD) and have been observed in association with angiodysplastic lesions in 2%-4% of patients with VWD. GI bleeds are closely associated with the absence of higher molecular weight and ultra-large multimers (ULMs) of von Willebrand factor (VWF), which are most often seen in patients with type 2A and type 3 VWD. Higher doses and longer durations of therapy with plasma-derived VWF replacement concentrates are usually needed to resolve GI bleeds compared with bleeds at other sites, and treatment may still be unsuccessful.